This invention relates to a disk centering apparatus, and more particularly to a disk centering apparatus for centering and mounting a disk-type recording medium.
A disk recording and/or playback apparatus records and/or plays back an information signal onto and/or from a disk-type recording medium. A disk recording and/or playback apparatus of the type mentioned includes a disk centering apparatus for mounting a disk-type recording medium in a centered state.
In order to assure a high degree of accuracy in centering a disk-type recording medium, a conventional disk centering apparatus includes a movable member mounted for movement in an axial direction of a motor shaft, and the movable member is inserted in a center hole of the disk-type recording medium.
An example of the conventional disk centering apparatus of the type described is shown in FIGS. 1 and 2.
Referring to FIGS. 1 and 2, the conventional disk centering apparatus a shown includes a disk table member b, a guiding member c, and a movable member d.
The disk table member b is formed as a unitary member from an annular fixed portion e, an upright portion f extending upwardly from an outer peripheral edge of the fixed portion e, and a receiving portion g extending outwardly from an upper end of the upright portion f. A recess h is defined by the fixed portion e and the upright portion f and is open upwardly. The disk table member b is secured at the fixed portion e thereof to an intermediate potion in an axial direction of a motor shaft i of a spindle motor not shown.
The guiding member c has a truncated conical shape such that the diameter thereof increases downwardly, and has a magnet j embedded therein. The guiding member c is secured to the top end of the motor shaft i.
The movable member d is formed as a unitary member from an annular base portion k and a receiving portion l of a truncated conical shape provided on the upper side of the base portion k. The receiving portion l is formed such that the diameter thereof decreases upwardly, and the outer periphery of the receiving portion l has a size equal to that of the outer periphery of the bottom end of the guiding member c.
The movable member d is supported for sliding movement on the motor shaft i between the fixed portion e of the disk table member b and the guiding member c. A compression coil spring m is interposed between the bottom surface of movable member d and the top surface of the fixed portion e and normally biases the movable member d to move toward the guiding member c.
Referring particularly to FIG. 2, when a disk-type recording medium n is moved downwardly so that it is mounted onto the disk centering apparatus a, the guiding member c and the movable member d are successively inserted into a center hole o of the disk-type recording medium n. Thereupon, the disk-type recording medium n is contacted at a lower side opening edge of the center hole o thereof with the receiving portion l of the movable member d and moves the movable member d downwardly against the biasing force of the compression coil spring m until the bottom surface of the disk-type recording medium n is brought into contact with the receiving portion g of the disk table member b. At this time, a chucking pulley p formed from a magnetic metal material is attracted to the magnet j embedded in the guiding portion c so that the disk-type recording medium n is held and mounted by and between the chucking pulley p and the disk table member b.
When the disk-type recording medium n is in the mounted position, the movable member d is at its downwardly moved position and the disk-type recording medium n is placed on and received by the receiving portion g of the disk table member b. Consequently, the disk-type recording medium n is positioned appropriately in the vertical direction in FIG. 2. Further, since the lower side opening edge of the center hole o of the disk-type recording medium n is received by the receiving portion l, even if the center hole o is formed with some dimensional tolerance by working, the eccentricity of the disk-type recording medium n in its mounted position is suppressed to the minimum.
Since the eccentricity of the disk-type recording medium is suppressed to the minimum in this manner, even when it is rotated at a high speed, a recording operation and a playback operation onto and from the disk-type recording medium can performed appropriately.
With the conventional disk centering apparatus described above, however, since the guiding member c is formed as a separate member from the movable member d and secured to the motor shaft i, where the disk-type recording medium to be mounted has a rather small center hole, the lower side opening edge of the center hole may possibly be caught by the guiding member c thereby to hinder the disk-type recording medium from being mounted as seen in FIG. 3.
It is therefore an object of the present invention to provide a disk centering apparatus which assures appropriate centering of a disk-type recording medium irrespective of the type of the disk-type recording medium.
In order to attain the object described above, according to an aspect of the present invention, there is provided a disk centering apparatus, comprising a disk table member including a substantially cylindrical inner circumferential element secured to an upper portion of a motor shaft and a substantially annular outer circumferential element disposed lower than an upper surface of and concentrically with the inner circumferential element and having a diameter greater than that of the inner circumferential element, the outer circumferential element having an upper surface which serves as a receiving face for receiving a disk thereon, the disk table member further including a plurality of connecting elements extending radially from an outer side of the inner circumferential element to connect the inner circumferential element and the outer circumferential element to each other, and a movable member including a substantially cylindrical supported shaft element mounted for sliding movement on the motor shaft, the supported shaft element being disposed lower than the disk table member, the movable member further including a guiding element provided adjacent an outer circumferential surface side of the supported shaft element for movement together with the supported shaft element and fitted in a space defined by the inner circumferential element, the outer circumferential element and the connecting elements of the disk table member, the guiding element having a guiding inclined element formed at an upper portion thereof for guiding a center hole of the disk, the guiding inclined element having a diameter greater than that of the inner circumference element of the disk table member, the movable member being biased upwardly in a direction of the motor shaft.
According to another aspect of the present invention, there is provided a disk centering apparatus, comprising a substantially cylindrical inner circumferential element secured to an upper portion of a motor shaft, a substantially annular outer circumferential element disposed lower than an upper surface of and concentrically with the inner circumferential element and having a diameter greater than that of the inner circumferential element, the outer circumferential element having an upper surface which serves as a receiving face for receiving a disk thereon, a plurality of connecting elements extending radially from an outer side of the inner circumferential element to connect the inner circumferential element and the outer circumferential element to each other, and a movable member disposed at a position defined by the inner circumferential element, the outer circumferential element and the connecting elements for connecting the inner circumferential element and the outer circumferential element to each other, the movable member having a guiding inclined portion formed at an upper portion thereof for guiding a center hole of the disk, the movable member being slidably movable in a direction of the motor shaft, the inner circumferential element, the outer circumferential element and the movable element being formed as a unitary member.
With both of the disk centering apparatus, even if the center hole a disk-type recording medium to be mounted onto the disk centering apparatus is formed with some dimensional tolerance in diameter by working, the eccentricity of the disk-type recording medium in its mounted position can be suppressed to the minimum.
Further, since the guiding portion is moved, even if the disk-type recording medium to be mounted has a rather small center hole, it can be mounted at an appropriate position with a lower side opening edge of the center hole contacted with the guiding portion. Consequently, the disk-type recording medium can be mounted with certainty and can be centered appropriately irrespective of the type of the disk-type recording medium.
The above and other objects, features and advantages of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings in which like parts or elements denoted by like reference symbols.